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The duodenum can be obstructed by atresia, stenosis, and pressure due to an extrinsic mass.
This anomaly is the 3rd most common atresia of the GI tract. The estimated incidence is 1 in 20,000 to 40,000 live births. Duodenal atresia is due to the failure of canalization of the embryonic duodenum. About 25 to 30% of infants with duodenal atresia have Down syndrome. Other congenital anomalies, particularly malrotation of the intestine, are present in about 65% of infants with duodenal atresia.
Diagnosis can be suspected prenatally if there is polyhydramnios, dilated bowel, ascites, or a combination. Infants with duodenal atresia present with polyhydramnios, feeding difficulties, and emesis that may be bilious. The diagnosis is suspected by symptoms and classic double-bubble x-ray findings—one bubble is in the stomach and the other is in the proximal duodenum; little to no air is in the distal gut. Although an upper GI series provides definitive diagnosis, it must be done carefully by a radiologist experienced with doing this procedure on children to avoid aspiration and is not typically necessary if surgery is to be done immediately. If surgery is to be delayed (eg, because other medical issues, such as respiratory distress syndrome, need to be stabilized), a contrast enema should be done to confirm that the double-bubble sign is not due to malrotation. Once the disorder is suspected, infants should receive nothing by mouth, and an NGT should be placed to decompress the stomach. Surgery is the definitive therapy.
These anomalies may obstruct the duodenum by extrinsic pressure.
Infants with choledochal cyst classically present with a triad of abdominal pain (a very difficult finding to infer in the neonate), right upper quadrant mass, and jaundice. If the cyst is large, it may also manifest with variable degrees of duodenal obstruction. Choledochal cyst is most commonly diagnosed by ultrasonography. Treatment is surgical and requires complete excision of the cyst because of the risk of developing cancer in the cyst remnants.
Annular pancreas is a rare congenital anomaly, often associated with Down syndrome, in which pancreatic tissue encircles the 2nd portion of the duodenum, causing duodenal obstruction; manifestation is usually during the neonatal period but may be delayed until adulthood. Neonates present with polyhydramnios, feeding problems, and emesis that may be bilious. The diagnosis can be suggested by an x-ray of the abdomen showing the same double-bubble sign seen in duodenal atresia. The diagnosis can also be made by an upper GI series and is more definitively made with CT or MRI. ERCP can be done in older children. Treatment is surgical bypass of the annular pancreas with duodenoduodenostomy or gastrojejunostomy.
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